大象传媒

We know that the CO2 increase is down to humans.

"1)
A drop of the 14C/12C ratio of atmospheric CO2. The Suess effect,first observed and accounted for, by Hans Suess in the early 1950s. The Suess effect happens because fossil fuels do not contain 14C precisely because they are fossil so they are much older than 10 half-lives of 14C.
2)
A drop of the 13C/12C ratio of atmospheric CO2. Because fossil fuels, forests, and soil carbon come from photosynthetic carbon, which is strongly depleted in 13C.
3)
A drop in the oxygen concentration of the atmosphere, the signature of an oxidation of carbon. Were ocean warming responsible for the CO2 increase, we would also observe an increase in atmospheric O2."
4)
The Oceans are acidifying due to uptake of CO2. So they are not the source.
5)
Volcanoes?

"...in the recently published eruption chronology of Hirschboeck (1980), a volcanic input of about 1.5 x 10^11 moles CO2 yr-1 was determined for the period 1800-1969. The period 1800-1899 had a somewhat lower input than 1900-1969, which could well be related more to completeness of observational data than to a real increase in volcanic CO2.

This input is well below man's current CO2 production of 4-5 * 10^14 moles CO2 yr-1."

Why might we suspect CO2?

We have had 0.6degC of warming since 1970, at about 0.2degC/decade

During that period we know there has been no increase in solar radiation, and no trend in cosmic rays, thus ruling out the Sun, which is well correlated with earlier warmings/cooling.

During that period we have also observed a gain in ocean heat content, this is generally global, climate cycles like El-Nino or the hypothesised Atlantic Ocean Oscillation move energy around, they don't lead to long term changes in the energy balance of the planet.

The stratosphere is cooling, it'd warm if the sun were causing the warming. CO2 is theorised to cool the stratosphere.

Models attribute the warming since 1970 to CO2. (Coincidence?)

The theory that more CO2 leads to a warmer planet has withstood every challenge since it was proposed by Svante Arrenhuis in 1896.

etc etc...

I agree Julian.

There is more to this than just CO2, but with CO2 in the background, and the long term nature of it's threat. There may be an understandable feeling that we'd be tidying up the garden before a hurricane comes to undo our hard work.

That said James Annan of JAMSTEC (Japanese climate modelling centre) makes a fair argument about horse dung in 18th century london. At that time, by very reasonable extralopation, dung may have seemed like a serious coming problem. It was impossible to know that the internal combustion engine was coming, thus removing the problem. But there are over ~4000 Gigatons carbon of extractable fossil fuels, we've used 300Gtons carbon of fossil fuels. So given the great availability and cheapness of coal, any 'combustion engine' type solution possible in the future would have to be cheap enough (in terms of energy invested for energy produced)to rival coal. I'm not holding my breath on that.

The CO2 issue remains mainly a long term threat (probably) with catastrophic potential scenerios. For example it's quite possible we can melt much of Greenland and the West Antarctic ice sheet, this would imply tens of metres of sea level rise. However given the slow speed of such a process (ice melt takes a lot of energy) it's at least a century plus timescale for impacting the majority of us. Yet we keep seeing it mentioned in the press!

In the short term (decades), from what I read, species and ecosystem impacts are more likely to be due to human impacts other than global warming due to CO2.

Sorry for another long post.

Hello John,

The problem is that this is all so basic and was settled long before the internet age. So the references are sparse and my old university doesn't have them, so I have no access to the actual papers.

Arrhenhuis' paper of 1896 is available here:

Arrhenhuis' proposal was challenged on the basis of absorption spectra, but the objection was based on spectra at sea level temperature and pressure, not the conditions in the troposphere. There's a discussion of this here: (But AIP seems to be down right now - hope the link is still valid.

Google "CO2 laser" to see an alternate and well-examined practical use of the physics that involves CO2's spectrum and the underlying physics.

I haven't followed the physics of this down to the level of theory in quantum physics. I really don't see any point. In the field I am have a degree in (electronics) it's quite apparent that the underlying physics is a tight web of theories. If one of the earlier theories ever seems wrong, it's always a fault elsewhere.

As in carpenting something like a staircase, the proof of the accuracy of making the parts lies in whether the whole thing fits together.

Hello John,

Yes Svensmark has done experiments.

You could do one too. Taking 2 bottles one with CO2 in it one with air. Put them in direct sunlight next to each other and the one with CO2 warms more.

The problem with both the above experiment and with Svensmark's experiment is that the real atmosphere is way more complex. Both experiments demonstrate that in the effects work in principle. But in the case of CO2 the atmosphere is far from all CO2. And in the case of CRF (cosmic ray flux), CRF is far from being the only source of cloud condensation nuclei.

I've read most of Svensmark's recent papers on the subject. "The Antarctic climate anomaly and galactic cosmic rays" is typical. It starts off talking about cosmic rays, then it shows clouds as being involved in the cooling of regions of Antarctica, then it finishes talking about cosmic rays. BUT, and it's a very big but, at no point does it show that the cloud changes are due to cosmic rays. Thus it fails to do what the person presenting it to me claimed it was showing; that the Antarctic cooling was due to CRF. There is research (sorry I've clean forgotten the name of the paper) that shows the cooling is due to the behaviour of the Antarctic polar vortex, now that could also cause a change in clouds. So you don't need to resort to CRFs to explain it. But more to the point Svensmark doesn't do so.

I agree with your implication that the power of politicians is limited (Curtis' "The Trap" which concluded on 大象传媒2 last night has an interesting take on this). In view of the global market, and the intense competetion it causes. I think that as oil and gas deplete and their costs go up we'll see a global transition back to coal. Coal could be used as the base energy source for a 'hydrogen economy' it can also be used to make gas (like "town gas") and via processes like Fischer-Tropsch it can make oil. Only where 'renewables' are cheaper can we expect to see them challenge fossil fuels. At the least, when burnt coal makes significantly more CO2 per joule of energy than oil/gas (conversion processes are worse).

Needless to say I hope I am wrong on that as much as I hope I am wrong on CO2 driven climate change. But that's a hope, not an evidenced conclusion.

Regards

Hello John Cooknell,

If you used a somewhat more meachnically rigid container and reduced the pressure you'd find more of a response. That's the situation in the troposphere above the boundary layer. And as the temperature here at the ground is affected by the temperatures aloft. Tropospheric warming still impacts. There's a basic tutorial here: (specifically 2.3.3)

Sorry I still find the Y2K issue irrelevant. Neither that, nor the claimed ice age scare in the 1970s, were long-standing science. Furthermore they had not been subjected to the intense attack the science of climate change has been.

Jon,

If you prefer the idea of 'random walks' then you will of course have no problem with the science of modelling. The models do not numerically extrapolate. Issues such as Random Walk are key to the way they iteratively apply the physics. Without that they wouldn't produce the agreements with observation that they do.

大象传媒 Censorship? Like the censorship of those claiming the Universe revolves around the Earth, miasma causes disease, humans didn't evolve from apes...

Sorry there's no censorship, it's just that unlike Channel 4, the 大象传媒 are making efforts to stick to the findings of science.

Hello Angela,

We know that all of the increase in CO2 has come from humans. some of the reasons given here:

So when the media talk of a certain percentage of CO2 they normally mean a percentage of total annual emissions (typically fossil fuel emissions). And as when we burn fossil fuels we are burning carbon fixed millions of years ago, by definition; all of our emissions are additions to natural budgets.

Terrestrial biosphere ~ 500 Gton.
Soils ~ 1500 Gton
[Siegenthaler and Sarmiento, 1993].

So as we have emitted about 300Gton fossil fuel Carbon so far(since 1880), our impact is not negligible. Especially as most of that has been absorbed by the oceans and the ocean surface is in a chemical equilibrium with the air: The oceans can return CO2 into the atmosphere more directly than land and soil.

We could reference all temperatures to some 4.5billion years ago. Against a few thousand degrees C current temperatures are negligible thus any changes are all the more so. So there's nothing to worry about if the planet boils, that's only a ~10% change.

With regards the Little Ice Age / Medieval Warm Period. There is no evidence to show that the temperature excursions then were likely as large and as sharp as todays, e.g. Moberg et al 2005: "Highly variable Northern Hemisphere temperatures reconstructed from low and high resolution proxy data "

And bear in mind, that's for the Northern Hemisphere. The global average temperature changes less because of the thermal buffering of the large ocean surface area in the southern hemisphere.

Surely it's reasonable for us to compare with the most recent periods for which we have good records?